The product ion and the application of polyolefins have been greatly developed in conjunction with the invention of a catalyst that is called Ziegler-Natta catalyst, and production processes and purposes of products have been developed in various fields. In particular, as the activity of the Ziegler-Natta catalyst is largely improved, polyolefin products using various single active point catalysts are developed in the art. Examples of the single active point catalyst include a metallocene catalyst, a Constrained-Geometry-Catalyst (CGC) of Dow, Co., Ltd., and catalysts using late transition metals.
In the copolymerization reaction of ethylene and alpha-olefin, excellent characteristics that the CGC has, as compared with (per se) known metallocene catalysts can be usually classified into the two categories: (1) it produces a high molecular weight polymer with high activity even at a high polymerization temperature, and (2) it yields very excellent copolymerization of an alpha-olefin having high steric hindrance, such as 1-hexene and 1-octene. In addition, upon polymerization reaction, several characteristics of CGC have been gradually noticed, and thus extensive studies to synthesize a derivative of CGC for use as a polymerization catalyst have been made in the academic and industrial fields.
As one approach, there have been trials for synthesis of metal compounds to which various bridges and nitrogen substituents instead of silicon bridges are introduced, and polymerization using the same. Some representative examples of recently known metal compounds include the following compounds 1 to 4 (Chem. Rev. 2003, 103, 283):

To the above-listed compounds 1 to 4, a phosphorous bridge (1), an ethylene or propylene bridge (2), a methylidene bridge (3), and a methylene bridge (4) are each introduced, instead of the silicon bridges in the CGC structure. However, when they are used for ethylene polymerization, or copolymerization with an alpha-olefin, they had no excellent results regarding the activity or the copolymerization performances, as compared with CGC.
As another approach, there have been trials for synthesis of many compounds comprising an oxido ligand instead of the amido ligand of the CGC, and sometimes polymerization using the same. Examples thereof are summarized as follows:

The compound (5) is characterized in that a Cp (cyclopentadiene) derivative and an oxido ligand are bridged via an ortho-phenylene group, as disclosed by T. J. Marks, et al. (Organometallics 1997, 16, 5958). Also, a compound having the same bridge and polymerization using the same are disclosed by Mu, et al. (Organometallics 2004, 23, 540). Further, an indenyl ligand and an oxido ligand are bridged via an ortho-phenylene group, as disclosed by Rothwell, et al. (Chem. Commun. 2003, 1034). The compound (6) is characterized in that a cyclopentadienyl ligand and oxido ligand are bridged through three carbons, as disclosed by Whitby, et al. (Organometallics 1999, 18, 348), but these catalysts are reported to exhibit activity on syndiotactic polystyrene polymerization. Further, similar compounds are also reported by Hessen, et al. (Organometallics 1998, 17, 1652).
The compound (7) is characterized in that it exhibits activity on ethylene polymerization and ethylene/1-hexene copolymerization at a high temperature and a high pressure (210° C., 150 MPa), as disclosed by Rau, et al. (J. Organomet. Chem. 2000, 608, 71). Further, synthesis of a catalyst having the similar structure (8), and polymerization at a high temperature and a high pressure were filed in the patent application by Sumitomo (U.S. Pat. No. 6,548,686).
It is reported that a ligand that has two cyclopentadiene-type anion frames shows high activity in the case of when a catalyst in which a transition metal compound (hereinafter, referred to as “metallocene”) of Group 4 of the periodic table and methyl aluminoxane or the specific boron compound are used as a cocatalyst is used to polymerize olefins. In addition, it is reported that a polymer having a narrow molecular weight distribution and composition distribution is produced, which is commercially advantageous.
In addition, in non-metallocene systems, in 1999, Fujita, T. et al. of Mitsui Chemicals, Co., Ltd. introduced a salicylaldimine ligand in which various substituents are present in an amine element, and announced in EP 0874005 that the ligand is a catalyst system having the very high polymerization activity to olefins such as ethylene, propylene and the like. In the same year, they announced in JP11-158189 that a transit ion metal of Group 4 is introduced into a hydroxybenzylamine ligand by reducing the salicylaldimine ligand, thus the ligand is a catalyst system showing the polymerization activity to olefins.
In addition, it is reported that in a catalyst for polymerizing, which includes a transition metal compound of Group 4 of the periodic table having one cyclopentadiene-type anion frame and a ligand where the frame and a nitrogen atom are crosslinked with each other by a silicon group and methylaluminoxane or a specific boron compound, in the polymerization of olefins, a polymer having the high molecular weight is produced with high activity (Japanese Unexamined Patent Application Publication No. 1991-163088, and Japanese Unexamined Patent Application Publication No. 1991-188092). However, the transition metal compound, particularly, in the case of when it has a crosslinking structure, synthesis of the ligand is difficult to perform, a plurality of processes is required, and a complexation process is not easily carried out.
However, among the above catalysts for polymerizing olefins, only few catalysts are substantially in use for commercial plants. Thus, there is still a need of development of a catalyst having a novel structure, and production of a polymer using the same. Particularly, the conventional binuclear catalyst compounds still have structures in the CGC form, and the method for producing the same is complex and the product ion yield is low. Therefore, there is still a desire of a binuclear transition metal compound having a novel structure, which is capable of exhibiting a catalytic activity, and a method for simply producing the same in high yield.